Telephone-exchange system.



I G. L. ZAHM.

TELEPHONE EXCHANGE SYSTEM.

APPLIOATION FILED SEPT. 19, 1905.

Patented Nov. 2, 1909.

3 SHEETS-BHEET 1.

Witumoeo U. L. ZAHM. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED SEPT. 19, 1905.

Patented Nov. 2, 1909.

3 BHEETB-SHEET 2.

3mm C01,

G. L, ZAHM.

TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED SEPT.19, 1905.

938,541 v Patented Nov.2, 1909.

' 3 SHEETS-SHEET 3.

Witnesses 3 i l Application filed September 19., 1905: Serial No.279,123.

- unirnnsrarps rarnnr OFFICE.

oHAnLiis L. zAHM; or'Los ANGELES, CALIFORNIA, Assrenoa or ONE-FOURTH'ro- EDWARD n CLEMENT, or WASHINGTON, msrnrc'r or COLUMBIA.

TELEPHONE-EXCHANGE SYSTEM.

To all whom'vlt-may concern:

Beit known that 1,.CI1ABLES 'L; ZAHM, a citizen, of the United States,

State. of California,-have inventednew and useful Improvements changeSystems, of which the following'is a specification.

My invention relates to telephone ex.-v change systems, and has foritsiobject to produce means whereby subscribers working on an automaticsystem may trunk directly into the manual system, without making anysubstantial change in either the automatic or ,manual .equipment, butretaining allthe advantagesof both. v

According .to one arrangement I cause a subscriber who comes in on afirst selector of the well known-'Strowger type, to select an idlesecond selector switch through which connection maybe had directly to amanual switchboard through axtrunk'line, or, if-

desired, any of the ordinary connector switches maybe reached andthrough any of them the call may also bemade to a sub scriber who mayalso have manual switch board -conne'ctions., With this arrangement itmust be obvious that I obtain a verygreat degree of flexibility in mysystem. possible through the second selector to get onto a toll board,

the tool or other manual My invention is illustrated in the accompanyingdrawings, wherein,

Figure 1 shows indlagram a subscribers' station, a standard lfirstselector-switch. of

Strowger type, and a second selector switch of thesame type-wherein Ihave made cer-. tainchanges so as to be-able totrunk. d1-

rectly to a manual switchboard. Fig. 2 is a similar diagramshowing-fatr11nk'. ack, -on. the manual sw tchboard. with the connectlveI -cord clrcuit and also a scribers' station with its linel terminatingon a manual switchboard Fig. 3;is a simi.-

lar. diagram showing a Strowger connector switch wlth certain changes,-which allow Specification of Letters Patent.

residing at Los Angeles,-.1n the county of Los Angeles'and in TelephoneExinformation. apparatus, etc.. with expedition and certainty; while Thefirst selector switch Z -lar Strow'ger type without change, need notcommon battery sub Patented Nov, 2, 1909.

,V Whose line terminates in a Referring now to vFig. 'l, the subscribersI station A isequipped with apparatus usually v found in local batterysystems, consisting of the transmitter T, receiver R, hook H, and

. ringerQ. In addition to the foregoingtalk ing set there is added thesending apparatus .for' transmitting impulses to operate the switches atcentral. I have .for I represented the sending apparatus by the two pushbuttons K, K. when depressed grounds number. 1 side of the line, andsendsimpulseswhich operate vertical relays in the various switches,while the button K when depressed ,sendsin an impulse over number 2 sideof the line which operates the rotary'relays. At the end of theconversation, both buttons are depressed sending in an impulse-over bothsides of the line simultaneously, afiecting both the verti- Simplicity1' The button K cal and rotary relaysand releasing thevarivousjswitches. Button K, when depressed,

after sending in the last set of impulses, o crates the ringing relay inthe connector switch.

V The switches I employ at thecentral oflice are preferably of the'Strowger type.

shown in Letters Patent Nos 815,176 and 815,321 to Keith and Erickson,dated March 113, 1906, although Ido not limit myself thereto, reservingthe right to employ others Where desired, with the necessarynon-essential" changesin circuit-s and connections.

being the rogu be described in detail. The vertical relay S responds. toimpulses over one side of the -line,.and operates the vertical magnet Ewhose armature 0 controls a pawl which engages a ratchet on thespindle zcausing it to step up in a vertical position. This spindle carriesthe'trunk w per-s12, 2 andthe The rotary. relay S responds to whichcauses themechanically voperated side ,switches s, 2 stand ,2 to turnone point, cutting-on. the rotary ma 'net D w hfi turn movesthe sideswltclies another oint connecting the line wires to the trunk Wipers.

The'release relay X is connected to the test wiper a 'and' controls thecircuit of the release magnet W which, when operated, restores theswitch to its normal position.

In the second selector switch Z wherein part of my invention lies, Ihave inserted additional apparatus and wiring which enables me to signaland be connected to a manual exchange without the necessity of using theordinary connector switch. I will point out the additions and changes asI proceed with the description. The vertical relay S which responds toimpulses over the vertical side of the line, operates the magnet E whichsteps up the spindle .2 vertically, in the same manner as described forswitch Z. The rotary relay S which responds to impulses over the rotaryside of the line, operates the relay A, which I have inserted. Onetcrminal of this-relay is connected directly to battery, while the otherterminal is connected to the ring of a trunk jack on a manual.

switch-board. The trunk wires 25 and 26 are continued through to the tipand sleeve springs of the same jack. I have also added the two normally.closed contact springs .12 and :0 to the release relay B1, so that instead of the spring 8 of the relay S being connected directly to thespring f of the re lay F it is connected indirectly through these twoadditional contacts. In addition to theforegoing, I have added the threecontact springs 2 2 and 2 which are 0perated mechanically by the spindlea To the contact 2 I have connected the terminal of the release relay Xwhich leads to the private wiper 2. The normally open con tact a isconnected to one terminal of the lamp L on the manual switchboard Fig.2. I have connected the firstcontact in the sideswitch a to batterythrough the contacts of the relay A, the reason for whichwillbecxplained later. l

Referring now to Fig. 2, I- have shown the manual switchboard end of thetrunk which consists of the lamp L and jack J having the tip spring 7',sleeve spring 7', and ring f.-

The cord circuit which forms the connecting link between the secondselector switch and the subscriber whose station is equipped with plug Pby the following path: 101, condenser C 103, contacts 0?, 0*, 105, to7). The ring p ,of the plug is connected to ground by the wire 113. Therelays K and K are connected to the tip and sleeve respectively, of theplug P,'and are connected permanently to battery at their middle pomts,

while the other terminals are connected to normally open contacts. Bothof these relays are of the locking type, and each one controls thecircuit of the lamp L. The relay K after becoming locked, is releasedmanually by the operator throwing forward her listening key which opensthe circuit of the relay. The-relays K, K are connected to the tip andsleeve of the calling plug P ,w respectively, one terminal of the relayK being connected to grounded battery, and one terminal of the relay Kbeing connected to the free side of batte thus supplying current fortalking to the called subscriber; These two relays jointl control thecircuit of the lamp L e relay K cannot become locked unless the'callingplug P'is inserted in the jack of 9. called line which energizes therelay K, closin the locking circuit of the relay K, so it'fo ows thatafter this rela becomes locked it cannot be released unti the callingplug is withdrawn from the jack, denergizing the relay K The subscribersstation A is equipped with apparatus usual in common battery systems,which consists of the trans mitter T, receiver R, hook H, ringer Q, and

condenser C; The wires from t is station terminate ina central office ona line relay M throu h the normally closed contacts of the cut-oil relayN. This relay when energized upon the insei ion of the plug P, attractsits armatures, disconnects the line rela and connects the line wires tothe springs 3 7''- cf the jack J'.

Referring now to 3 I have shown a connector switch Z wherein I haveadded apparatus and wiring which in connection with the equipmentalready described in Fig. 2 enables me to call automatically 8.subscriber in a common battery exchange. I V

will point out as we go along the additionsand changes I have made. Thevertical reside of the line, operates the vertical magnet E causing thespindle z to step up vertically The rotary relayS" responds to imsecondpoint in the switch z".- This second v lay S responds to impulses overthe vertical ave point in the Strowger system is connected to a normallyopen contact in the private relay F and the contact which engages it isconrelay connected to the ing connected to the free side of the battery.

Battery being thus bridged between the two windings suppliestalkmg'current to the subscrib'er 1n the manual system, and also fur--nishes means for pulling up the cut-off relay,

- therelay S";

I connects disconnecting the line signal, and providing a busy test aswill be explained later.

In the Strowger system, the arm of the side-switch e is connecteddirectly to the private wiper 2", but between these two points Ihave-insertedthe release relay 'X having the contact an grounded, andthe .contact a connected to one terminal of therelease magnet and to thecontact 8 of It will be seen that instead of having-the magnet IV act asthe test as in the Strowger system, local circuit of the relay X to, orbecomes energized, by 015 current such as would be a small amountreceived in test ing a busy line in a manual system." The test in suchcases is generally produced by the difference in potential between tworelays or coils. spon'd to'such currents" as it is simply built andrequires a certain amount of currentvto operate. I have not changed thecircuits of the ringing relay Y in the slightest, which when becomingenergized opens the calling end of the trunk and generator current tothe calling end.- I'have connected the test contacts 2 which in theStrowger system are normally free from any connection, to the tipcontacts of the lines in the manual exchange which are in parallel withthe multiple and jacks of the manual switchboard. Thetip and sleeve.contacts in the switch are coin nected in parallel with the tip andsleeve springs respectively in the same answeringand multiple jacks.

In the operation of thatpart of my system where a connection in a commonbattery manual exchange where the conditions are such that hecannotcallthe subscriber automatically,the procedure is as follows: Heis first connected, to a second selector switch and from there Strowgersystem have respectively, the other I have placed it in the whichresponds The magnet W will notre-' answeringcalling subscriber wishesfor a' operator completes the connection through her cordcircuit tothewanted subscriber.-

The calling subscriber first depresses the button K sending impulses,the numberof which will" correspond .to the exchange Wanted. Theimpulsescoming in over number I side of the line operate the relay S,which at tracting its armature closes the circuit of the magnet E- by the'following path: ground, 36, s,-s,v 34, f, f, 31, E, 35, t obattery B,The operation of this magnet causes the spindle 2 carrying thetrunk-wipers a, 2 and the test wipers and come-oppositearow ofcontacts'leadlng to a groupof second selector switches of my to step upvertically; I

changed typeewhi'ch have 'accessdirectly to,

a manual switchboard;

over number=2 side of the" line, operating, the relays, which in turncloses of the private relay Fby the follo ing path;

ground, 36, s, 8. 37, F, 38, to battery B This relay operating opens thecontacts f, disconnecting the verticalmagnetE andpre-,

yentingthe spindle z from making'a Verticalmovement, F also causes theto move one oint, and in the switch -The 'subs'criber now depresses abuttonfK, sendinganqimpulse;

'85.v the circuit;

The operation of the relay side-switches a, 2 z, 27,

at, clos 3 ing the circuit of the rotary magnet D. The

circuit of this magnetbeing'closed causes its armature to vlbrate, whichin turn rotates the spindle 2 until the Wiper a finds a con tactiu therow not busy, that is'to say, free from grounds. As soon as such'acontact is foulhd the relay F becomes deenergized and causes the sideswitches to take the third I position cutting off the rotary magnet Iand causing the spindle to come to reist with' the wipers on contactsleading to, an idle second selector. switch; fgized while the switch isrotating and the wiper ,2? is passing over -tacts by the following path:5, 44,37, F, 38, 35 tobattery X does not become energized on account ofits winding being and in series of The side switches in wires 1, 2 tothe wires the grounded-con- B.- The 'relay' of a verylow resistance;

.the winding of the relay F .which is of comparatively high resistance.f

10 5'. The relay F is keptener-,

3 and 4 respectively leading to the Wipers 2? I I and eiand ground thetest contact .2 \following path: ground, 65, toe. The calling subscriberis now con nected to a second selector I leads directly to a manualswitchboard; Instead ofsending inadditional set of impulses'henow'simply depresses the buttonKj "which in the ringing button. sends.an impulse ov'er operating the vertical the circuit of the verticalmagnet-E by the following path: ground, 8}, s 49, mt,

switch which ye ,,X, 435 5 i v v 2 Strowger system would be'the I [Thepushing of this button No.1 side of. the line relay S which closes f, f,47,1 3, 45 to battery B. The energiz- 1 mg of this magnet causes thespindle e to step up vertically to thefirst row of contacts, closing thecontacts z and 2 which 5 completes the circuit of the line lamp on theswitchboard b the following pathzxbattery B, 45, 61 a, a, a .62, 50, 257, X, 58, 59,. 2 2 2 27', lamp'L to ground. The re lease of thedifierent switches is effected by 10 :the release'magnet first becomingenergized and then deenergized thus constituting a two-step escapement.As the back release relay X is in series with the lamp L it becomesenergized and, attracting its armature,

16 closes the circuit of the release magnet W 53; the following path:ground, m :0 54, 60, to battery B. This magnet becoming energized takesthe first step toward releasingthe switch'Z. The contacts m and w 20 ofthe magnet X are broken, disconnecting the vertical magnet "E, thuspreventing the spindle z -from taking a second step in case t esubscriber should depress the button K the second time. The callingsubscriber has 2 5 now signaled and is connected to the manualswitchboard over No. 1 side of the line by the following path: 1, 2 3,e, 5, j of the jack J and over No. 2 side of the line by the followingpath: 2, z, 4, e 6, 26, to j of the jack J.

Referring now to 2, the operator at the manual exchange erceiving thelamp L glowing inserts the p 11g]? into the jack J throws forward herlistening key 0 in the ordinary manner, and asks for the number wanted,The insertion of this plug Hoses the circuit of the cut-off relay A inthe sec-U ond selector switch Z log the following path: ground, 113, p,j ,-28, 6,4, to battery B.

4 This relay becoming energized attracts its 1 armature opening thecontacts a, a, a disconnecting the vertical and rotary relays S and qand opening the'circuit of the back release relay X whose armature nowas sumes its normal position and opens the circuit of the release ma etW restoring the switch Z to its norma position. The spindle inreturning'to its normal position "opens the contacts 2 and eextinguishing thewsignal lamp L,

Referring a ain to'Fig. 2, the operator upon finding t e number wantedinserts the calling plug P into the jackJ of the desired line. Thisinsertion closes the circuit #5 of the relay K and the cut-off relay Nby the following path: battery B, 120, K 117,

0 0, 105, pfij', 124, N toground. The

I relay N becoming energized attracts its armatures and disconnects theline relay M 6.0 and connects the line wires 125, 126 to the The relay Kin becoming energized attracts its armature and closes the circuit ofthe supervisory lamp L and places a ground on the contact is of therelay K by the followin path: ground, is, 10 115, 7c. The

suhscriber at station A. upon answering closes his line circuitenergizing the relay K extinguishing the lamp L thus notifying theoperator that he has answered. At

the end of the conversation the subscriber at station A hanging up openshis line circuit, deenergizing the relay K causing the lamp L to againglow. The subscriber at the automatic station A in hanging up depressesI normal position. These same impulses operate the relays K and K inFig. 2 in a similar manner. The relay K attracting its armature closesthe circuit of the lamp L by the following path: ground, 70 is, 112,111, L, 109, to battery B and locks itself by the following path:battery B 109, 110, 108, K, 10 70 115, 118, 70 is to ground.

The operator upon perceiving both lamps glowing takes downtheconnection, that is withdraws both plugs P, P- from the jacks J, Jrespectively. The relay K now becomes deenergized extinguishing the lampL and releases the relay K which in turn extinguishes the lamp L. If thecalling subscriber wishes to signal the operator while theplugs are intheir respective jacks, he depresses the ringing button which sends inan impulse'over the vertical side of the line operating the relay Kwhich, attracting its armatures, closes the contacts is and is causingthe lamp L to flash. This relay K cann'ot lock itself at this timebecause the contacts 70 and is of the relay K are broken. Su pose thecalling subscriber hangs up be ore the operator has placed the callingplug P- into the jack J of the want ed line. Impulses coming in overboth sides of the line simultaneously operate both the relays K and Kbut looking only the relay K by .the following path: battery B, 109,

110, 108, K, e, k, 114, 0 0 119, I610, 16 to ground, The circuit of thelamp L is also closed and the operator noticing the lamp glowing throwsher key 0" into the listening position breaking the contacts 0 and '0releasing the relay K which in turn .extinguishes the lamp L.

It will be seen from the foregoing description that I have provided forany contingency which might arise while the subdisconnect the relays S?pressing the button K he private inagnet .F'

nected to asubscriber in a connnon-battery exchange through a manualswitchboard.

I will now describe the operation of that partof my invention wherein asubscriber in subscriber in acommon battery exchange .an automatic.exchange is enabled to 'call a i on the manual switchboard complete thecoir nection. This is done by callinggthrough to a connector switch ofmytype which I have described. This connector switch cooperates with theselector switches already described in Fig. 1. While I have' madecertain changes in the second selector-switch Z enabling me to beconnected directly to a manual switchboard it also can perform theordinary function as in the regular Strowger system by pickingout-theconnector switch of the desired hundred. I y

Ihave already described the operation of the first selector switch Z in-connectionwith the first part of my invention and itw'ill not benecessary to repeat it. e will take it for granted that thecallingsubscriber is connected through the first selector; switch toasecond selector switch of my type. -De- Y sends in impulses over No. 1side of the line operating; the relay S in the switch Z which in turncloses the circuit of the vertical magnet E by the following path:'gro'und, s", 8 49. m. 02 ,51}

f 'ffi 47. E" to battery B. This magnet in operating causes the spindlea to step up a row of'contacts leading 'to a connector switch of thedesired hundred. The subscriber now depresses the button' K sending animpulse over-No.2 side of the line operating the relay S which in turncloses the circuit of the ground, 8 s, 55, F, 63; 4'5, Thefmagnet F?becoming energized opens the contacts 7?, f disconnecting the verticalmagnet E" preventing the spindle", from making. a vertical movement.

by the following path to battery B.

The operat ing-of this relay causes the side switches a,

23?, a, 'to move one point closing the circuit of therotarymagnetD-which'causes the spindle tov rotate and continue to rotateuntil the wiper a finds 'a contact free from ground. F becomesdeenergized and "the contact of the connector switch upon which the Assoon asthishappens the relay' the side switches move anotherpointdisconnecting the rotary magnet causing the, wipers'to rest on con'tacts leading to an idle and ground priyate wiper-rests by the follow-1 mg path: 2 58, X', 57, to ground. The ca ling subscriber isnowconnected .to the connector switch the desired line;

The operation o f the containing the contacts I of .-.of the verticalmagnet E pressesthe button K" over No. 2 side of the line operating'therelay N. If I would connected to it visory relays of'the'operators cordcircuit on up vertically is much too rapidto cause the lamp L onl-themanual switchboard to glow and as soon as the switch makes asecondvertical movement its, circuitis broken at springs-c -a that is therelay X is' no longer 'connectedto thewire 27. This rapid j movement ofthe spindle inthe first step is without the necessityof having anoperator also too rapid to operativelyenergize the "connected to a.connector switch of the desired hundred, depressesthebutton K sending inimpulses over No 1; side of the line operating the vertical relay Swhich in turn closes the'icircuit of the vertical magnet E bythe-following path: ground, S "S 73, f, 7", 72, 2?, 85,13 92, 7S-tobatteryB. The operation of this ma net causes thespindle 2 to move upVerticajly bringing the wipers c",- .2 and 2: oppositethe rowcon'tamin'g4 the COIitaCtS'OftllG desiredline. The subscribernow depresses the-botOm K'- sending an impulse o'verNo. 2' side oflirieoperatmg the relay :3which in turncloses the circuit'of the relay F? by the'following path:

ground, 8*, 8 8 75,"F?,77, tobattery B. This relay opens the contacts f,f. dis,- connecting the vertical magnet E and cansing the side switches2 2 2 and a to rotary magnet I isnow connected infplace "The subscribernow depresses the butto'nK sending impulses over No. 1 side of theline-operating the re-.' lay Sthe second t-imvwhich now'in'turn .moveone point; Inthe side switch-2 the closes the circuit of.'the rotarymagnet I the'following path ground, 8 sf, 73, fflf, 72, at, 84, 1 92, 78 to battery, B. i This mag-T netinoperatingcauses the spindle torotate] bringing the wipers to restjon the contacts of the desired line.The subscriber now, de-' sending an impulse lay S which in turn closesthe circuit of the relay F as before and at thesame time pla'cing therelay} X 91, to wiper i2 and v y the contact 2 upon which it rests,

Normallythis contact as w'ill be"seen by referringiito the diagram", is"

open being. multip'ledto' p the tip spring of the multiple jacks J J? ina test position by the following, path? ground, 8 s", 76, 2 90, X

and from there to I the normally open c onta'ctyof the cut-off 're= thisline was busy. the battery through the superthe manual switchboard, Ifonjthe other hand" the line was engaged by another coni nector'switch'the' tip supplied 'withbatte'ry, throu retardatioiijcoil whichfurnishes the battery ppl in 'talk pu re side of line would be. gh thetalking or release magnet W restoring theswitch to its normal position.We will take it for granted that the line is not busy; The operation ofthe private magnet F the second time causes the side switches to moveanother point. In the side switchle the rotary magnet I is disconnectedand the ringing relay Y connected. in. its place. The trunk wires 11 and12 are connected res ectively to the trunk wipers z" and 2- tirougn thenormally closed contacts of the ringing relav Y. In the side switch 2the circuit of.

the relay X is opened. As soon as the trunk wires of the switch areconnectedto the wipers resting on the contacts of the desired line thecircuit of the cut-ofi relay N is closed by the following path: batteryB, 7 8, 82, one winding of the coil 1, 81, 12, a, 14, y, 3 ,16, 2 18,20, N to ground. This re lay becoming energized attracts its armatu're,disconnects the relay M and connects the line wires 21 and 22respectively to the trunk contacts 17 and 18. The calling subscriber isnow connected tothe desired party and depressing the button K'which nowacts as the rin ing button, he operates the vertical relay path; ground,s s 73, f, f, 72, 2

9, 78 to battery B. This relay becoming energized attracts its armature,disconnects the calling end of the trunkv and connects generator currentto the wipers leading to the-desired line. The subscriber in the com monbattery. exchange removin his telephone is supplied with battery i012talking pur oses through the windings of the retar ation coil 1. Thecondensers C and. G;

being inserted between the wires 9,11 and 10, 12- prevent battery fromflowing back over the trunk operating. the vertical and rotary relays.

At the end subscriber in hanging up. depresses the but tons K and Kgroundin (both sides of the line simultaneously "whic in the switch-Zoperate the relays S and S two relays becoming ener 'zed atthe sametimeclose the circuits 0 the release magnets'in the connector switch Z andin theisecend selector switch Z" in the following manner:

cit

First the circuit of the release"magne -VV is closed in series throughthe back release relav X by the, following path battery B,;78, W 87 88",. I4, 2 32 58, X, 57, e*,;to ground. -The magnet W? becomingenergized restores the switch Z to its normal position. The relay X.becoming fenergized attraetsits armature and closes the cir-' cuit ofthe release agnet'W by the' following path ound, 412 ,03, 54,53, W, tobat tery B. T is magnet becoming energized restores the switch Z toitsnornial position. In thefirst selectonswitch Z, the vertical androtary relays S and S are connected permawhich in turn closes thecircuit of the ringing relay Y bv the followiig' of the conversationtheicalling' nently to the trunk and the impulses coin lllg ll l overboth. sides of the line simulta neously energize these relays whichclose the circuit of the release magnet 'W by the fol:

lowing path: ground,.36, s, s, 34:, f, F. of the relay F ,as-it is enerized at this time, it), W, 35, to battery B; 1%16 energizing of thisrelay restores .the switch Z to its normal position.

It will be readily seen from the foregoing description that the secondselector switch Z is a combination switch, and performs two functions,vfirst in connection with a first selector. switch it connects thesubscriber directlytoa manual switchboard where he can be connected toany subscriber inthe manual common battery exchange.

The operator at the manual switchboard can also act in the capacity ofan information operator in case the subscriber desires some informationrelating to new subscribers or changes of numbers, etc. Second, thisswitch can be used as the ordinary second selector switch and connectthe calling subscriber directly to a connector switch which is operatedin the ordinary manner and enables him to call a subscriber in anautomatic exchange jorin picking out a group of selectors of my typehecan call a subscriber in the manual full common battery exchange in thesame manner as calling a party in the automatic exchange. v v 1 Havingthus described my invention, what Iclaim and desire to secure by LettersPatent of the United States is:

lector switches for interconecting the line.

with other lines as determined by the subscriber, one of said switchespermanently associated with and controlled by said subscribersline, amanually operated switchboard having trunk terminals and signalstherefor, a trunk-line permanently connected to one of said selectorswitches accessible by asingle selective operation from the subscribersswitch, and to one of said-trunk terminals on the manual board, withmeans whereby the-said signal may beset and connection obtainedthrougli'the manual switchbeard by a. single operation of thesubscribers switching apparatus, and further mean -whereby continued orrepe t p rlines without operating ations may eonnectthe line directly toother the trunk signal, substantiallyas described.

3.-In a telephone exchange system, a plurality of subscribers lines anda plurality of automatic switches for interconnecting them as determinedby repeated current changes caused-by the calling subscribers, one ofsald switches assoclated with. each line and, used as a'first digitselector, a plu-' requiring an appreciable time nal, substantially asdescribed.

4. In a'telephone exchange system, aasubscrib'e'rs line, a firstselector switch con-- trolled thereby and-having means to pick out andconnect with a, trunk to asecond selector switch, thence to furtherswitching;

means and to subscribers linesfautomatidally, a; permanent extenslon ofthe trunk troni the second selector to a manually operat'ed switchboard,ajconnective terminal and iISlLIlitl on saidboard for said trunkextension, and means whereby the second se lector switch may be advancedone step to.

display 'the switchboard signal, without clian sing the connection ofthe trunk, substantially as described. 4 c

In a telephoneexchange'system, a, sub

scribers line, a firstselector switch con-f trolled thereby, andliayingmeans to pick. out and connect with a" trunk'jto a secondselector switch, thence to further switching meansand tosubscribers"lines automatic;

ally,- a' permanent extensionof the' second se-. lector trunk to a,manually operated switchboard. a connective terminaland a signal,

on said board for said trunk. extension,

means operated in one step of the second select-or switchto set saidsignal to attract the attention of the operator, and means'controlled bythe operator to. release and restore the switch and thereby restore thesignal. substantially as described.

(5. In a telephone exchange system, a selector switch having "areleasemagnetop erating to release the switch mechanism,

means to control the switch-as determined by a calling subscriber, andmeans to select other switches and subscribers lines automaticallythereby, a perma11entconnection of the talkingcircuit of the selectorswitch to a manually operated switchboard and a signal thereon for thesame, whereby the talking circuit is complete when a line has selectedthe said switch without moving-its operating parts, means fordisplayingsaid signal on actuating the switch,'and means controlled by theoperator inanswering the call on the manual switchboard to cut oil anddecnergize said release magnet, whereby the switch will be restored andthe signal reset, substantially as described.

7. In an automatic telephone exchange system, a second'selector switch,means controlled by a subscriber to connect his line therewith andthence with other subscribers 1 i lines automatically, a back releaserelay for said switch,-and a release magnet 'cont1 olle d thereby,a'n'extension of the talking circuit of the switch to a manuallyoperatedswitchboard, a -signal on said board associated therewith, acircuit for said signal closed in the first mo'i ement of the switch andincluding the Saidback release relay to cause the,

initiation of the release movement when the signal'is'dlsplayed, acut-oft relay for the signal'and release relay circuit, and meansactuated by an'operator inanswering a call on the manual switchboard toenergize said cut-oil relay, substantially as described.

8. In-anautomatic telephone 'eXcl i ange' system, a selector switch,means controlled by a subscriber to select other subscribers throughsaidswitch, an extension of the circuit of said switch-teamanuallycontrolled switchboard, whereby a callmgsubs'criber ,can'connect his talking circuit to said manual switchboard without operatingtheswitch, a signal associated with the extension on the manualswitchboard, a circuit for'said signal closed in the first-move;

ment ofthe selectorswitch without affecting the talking-circuit, and acut-off relay associated with the selector switch controlled by theoperator in-answering a 'call on the;

switchboard, and-acting to cut elf the signal and restore the switch,substantially as de scribed. I

9. In an automatic telephone exchange system, aselector switch having atrunk,

means controlled by a subscriber. to connect hisline with said trunk andthrough the selector switch with other subscribers lines,

an extension of said trunk ."to a manual switchboard, a spring jackthereon and a- 7 signal associated with the trunk extension, a circuitcloser for saidslgna-l actuated m cut-off relay in the selector switchconnected to a contact in the springjack closedby the operator inanswering a call and acting to disconnect the controlling means in theswitch to leave a "clear, talking circuit and also meat on the signal,substantially asv described.

10. In a telephone s stem, at second selector switch having ridgedcontrolling the selector switch by the subscriber, and a,

magnets, a trunk accessible to a calling subscriber and connected togive control of said magnets and the switch, an extension of said trunkto a manually operated switchboard with a signal associated therewith, aspringjack for the trunk extension, opera tors plugs and cordscooperating therewith, a circuit closer for the signal operated in thefirst step up of the selector switch, a

release magnet therefor, and a cut-oft'relay in a circuit closed in thejack when a plug is inserted by the operator, whereby the controllingmagnets are cut off, the release is operated, and the signal is restoredsubstantially as described. 11. In a=telephone exchange system, aselector switch, controlling magnets therefor after the first impulserepeated im ulses by the subscriber will produce no e ect, substantiallyas described. 7

12. In an automatic telephone exchange system, selector switches andmeans con-' trolled thereby to directly interconnect sub scribers lines,an extension from a selector switch circuit to a manual switchboard andasignal therefor, a circuit closer for said signal actuated by the firstmovement of they switch, means at a subscribers station for sending arapid succession of impulses to set I up the switch, and means also tosend a single impulse to close ,the manual switchboard signal circuit,the succession of impulses being too rapid in every case to set theswitchboard signal, substantially as described.

13. A combined automatic and manual switchboard system ofthe typedescribed,

comprising a pair of connective terminals and cord conductors, withthree-bridged relays on opposite ends thereof and responding to currentin opposite directions to the connected stations, two bridged across oneend of the cord with a battery connection from a point between them, thefirst relay having a circuit whereby upon attraction of its armature itwill be self-locking through the listening key of the cord and anormally closed contact of the third relay, the second relay beingsimilarly self-locking through contacts normally open of said relays inthe third relay but closed when a connection is completed, substantiallyas described.

- 14.'In an automatic telephone exchange system, a plurality of selectorswitches and connector switches working therewith to seminals therein,vertical and rotary relays therein, manual switchboard connections andrelays for said subscribers lines, a sensitive test relay, and meanscontrolled by the rotary relay in a connector switch in completing aconnection with a called line, to connect said test relay to the testwier of the said connector switch, whereby di erences of potential on themanually connected lines described.

15. In a telephone exchange system, a subually operated switchboardhaving trunk line connective terminals and signals associated therewith,connections from said selector switch to said switchboard, meansacswitch to display a signal and indicate that board, and means actuatedonthe second substantially as described.

lector switch having a release magnet operto control the switch asdetermined by :11.

thereby, a permanent connection of the talkually -operated switchboardand a signal circuit is complete when a line has selecte the'said switchwithout moving its operating parts, means for setting the signal andclosing circuit tothe release magnet on thefirst step of the switch,means controlled by an operator in answering-a :call to cut oif anddenergiz'e the release magnet, and other means controlled in asubsequent step of the switch when making a selection other than ing thesame, substantially as described;

in presence of two witnesses.

CHARLES L. ZAHM.

5 Witnesses: g I

Gi-io. E. Hreems, Rm: GARRETT.

tuated in the first motion of the selector a connection is desired onthe manual switch-- 'motion orstep thereof to cutoff the same,

calling subscriber, and means to select ptheri switches and subscriberslines automatically ing circuit of the selector switch to a man-,

thereon for the same, whereby the talkin that of the manual operator, tocut oil the release magnet without effectively energizlect and connectwith subscribers line termay be detected in testing, substantially asscribers line, a selector switch controlled. thereby having-means toconnect the line by*' successive motions with other lines, a man 16. Ina telephone exchangesystem, a se-' ating to release the switchmechanism, means In testmmny, whereof I aflix my signature i

